Assessing connectivity contributions of urban green spaces for avian species conservation: Insights of a surrogate approach in Nanjing

Urbanization fragments habitats and isolates species, leading to significant biodiversity declines. While urban green spaces (UGS) play a crucial role in conservation, the assessment of their contributions to habitat connectivity has been limited, hindering effective urban biodiversity planning strategies. Within the urban core of Nanjing, we classified nine distinct UGS types to assess their roles in connectivity, specifically identifying where, to what extent, and how they contribute. Using a framework that integrates avian surrogate species evaluation and habitat identification with a circuit theory-based approach, we analyzed UGS contributions to omnidirectional species habitat connectivity. Our results reveal that natural vegetation predominantly supported connectivity in intensified areas, while artificial UGS, particularly in critical connectivity zones, provided nearly twice as much support for habitat linkages. Synergistic effects were observed among different UGS types, though their impact on connectivity varied. Notably, park and residential green spaces showed a spatial mismatch with connectivity patterns. Our findings emphasize the importance of incorporating connectivity-focused strategies into UGS planning, highlighting the need for an integrated framework for biodiversity conservation in urban development.